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The article discusses a study on the expression of LjFTa gene encoding an ortholog of Arabdopsis thaliana Flowering Locus T (FT) which plays an important role in the promotion of flowering and its regulation in Lotus (L.) japonicus. In the study, microRNA involved in the activation of LjFTa in L. japonicus was examined in context with the photoperiodic control of flowering time in A. thaliana. The study suggests that LjmiR172 genes promotes flowering in L. japonicus.

Thioredoxins are a ubiquitous family of redox equivalent mediators, long considered to possess a limited number of target enzymes. Recent progress in proteomic research has allowed the identification of a wide variety of candidate proteins with which this small protein may interact in vivo. Moreover, the activity of thioredoxin itself has been recently found to be subject to regulation by posttranslational modifications, adding an additional level of complexity to the function of this intriguing enzyme family. The current review charts the technical progress made in the continuing discovery of the numerous and diverse roles played by these proteins in the regulation of redox networks in plant cells. [ABSTRACT FROM AUTHOR]

The chloroplast-type F1 ATPase is the key enzyme of energy conversion in chloroplasts, and is regulated by the endogenous inhibitor ͛, tightly bound ADP, the membrane potential and the redox state of the γ subunit. In order to understand the molecular mechanism of ε inhibition, we constructed an expression system for the α3β3γ subcomplex in thermophilic cyanobacteria allowing thorough investigation of ε inhibition. ε Inhibition was found to be ATP-independent, and different to that observed for bacterial F1-ATPase. The role of the additional region on the γ subunit of chloroplast-type F1-ATPase in ε inhibition was also determined. By single molecule rotation analysis, we succeeded in assigning the pausing angular position of γ in ε inhibition, which was found to be identical to that observed for ATP hydrolysis, product release and ADP inhibition, but distinctly different from the waiting position for ATP binding. These results suggest that the ε subunit of chloroplast-type ATP synthase plays an important regulator for the rotary motor enzyme, thus preventing wasteful ATP hydrolysis. [ABSTRACT FROM AUTHOR]

In F1-ATPase, the rotation of the central axis subunit relative to the surrounding α3β3 subunits is coupled to ATP hydrolysis. We previously reported that the introduced regulatory region of the γ subunit of chloroplast F1-ATPase can modulate rotation of the γ subunit of the thermophilic bacterial F1-ATPase (Bald, D., Noji, H., Yoshida, M., Hirono-Hara, Y., and Hisabori, T. (2001) J. Biol. Chem. 276, 39505-39507). The attenuated enzyme activity of this chimeric enzyme under oxidizing conditions was characterized by frequent and long pauses of rotation of γ. In this study, we report an inverse regulation of the γ subunit rotation in the newly engineered F1-chimeric complex whose three negatively charged residues Glu210-Asp211-Glu212 adjacent to two cysteine residues of the regulatory region derived from chloroplast F1-ATPase γ were deleted. ATP hydrolysis activity of the mutant complex was stimulated up to 2-fold by the formation of the disulfide bond at the regulatory region by oxidation. We successfully observed inverse redox switching of rotation of γ using this mutant complex. The complex exhibited long and frequent pauses in its rotation when reduced, but the rotation rates between pauses remained unaltered. Hence, the suppression or activation of the redox-sensitive Fl-ATPase can be explained in terms of the change in the rotation behavior at a single molecule level. These results obtained by the single molecule analysis of the redox regulation provide further insights into the regulation mechanism of the rotary enzyme. [ABSTRACT FROM AUTHOR]

Vacuolar Ca2+/H+ antiporter VCAX1p, which contributes to the Ca2+ accumulation into vacuoles, was quantified by immunochemistry. The antiporter content in vacuolar membranes was 0.14 and 1.1 µg mg–1 of membrane protein for hypocotyls and epicotyls, respectively. The calculated turnover number was 120 s–1. Roots lacked the antiporter protein and the transcript. [ABSTRACT FROM PUBLISHER]

The Ca2+-transport activity and intracellular localization of the translation product of cDNA for mung bean Ca2+/H+ antiporter (VCAX1) were examined. When the cDNA was expressed in Saccharomyces cerevisiae that lacked its own genes for vacuolar Ca2+-ATPase and the antiporter, VCAX1 complemented the active Ca2+ transporters, and the microsomal membranes from the transformant showed high activity of the Ca2+/H+ antiporter. Treatment of the vacuolar membranes with a cross-linking reagent resulted in a clear band of the dimer detected with antibody specific for VCAX1p. The antibody was also used for immunolocalization of the antiporter in fractions obtained by sucrose-density-gradient centrifugation of the microsomal fraction from mung bean. The immunostained band was detected in the vacuolar membrane fraction and the slightly heavy fractions that exhibited activity of the Golgi marker enzyme. A fusion protein of VCAX1p and green fluorescent protein was expressed in tobacco cells. The green fluorescence was clearly observed on the vacuolar membrane and, in some cases, in the small vesicles. The subcellular fractionation of transformed tobacco cells confirmed the vacuolar membrane localization of the fusion protein. These results confirm that VCAX1p functions in the vacuolar membrane as a Ca2+/H+ antiporter and also suggest that VCAX1p may exist in the Golgi apparatus. [ABSTRACT FROM AUTHOR]

Examines the properties and molecular cloning of Ca[sup 2+]/H[sup +] antiporter in the vacoular membrane of mung bean hypocotyl. Increase of cytosolic calcium ions level; Role of calcium ions in the transduction of plant cells; Coexistence of two different systems of calcium ion accumulation in plant vacuoles.

The article focuses on a study related to the characterization of the promoter activity of Arabidopsis thaliana core clock genes CCA1 and PRR5 in heterologous Lotus japonicus cells. It mentions several methods including bioluminescence measurement, polymerase chain reaction and plant cell culture which are used as research methodologies. The result reveals that molecular mechanism of circadian rhythm in Lotus japonicus is compatible with that of Arabidopsis thaliana.

In photosynthetic water oxidation, two water molecules are converted into one oxygen molecule and four protons at the Mn 4 CaO 5 cluster in photosystem II (PSII) via the S-state cycle. Efficient proton exit from the catalytic site to the lumen is essential for this process. However, the exit pathways of individual protons through the PSII proteins remain to be identified. In this study, we examined the involvement of a hydrogen-bond network near the redox-active tyrosine Y Z in proton transfer during the S-state cycle. We focused on spectroscopic analyses of a site-directed variant of D1-Asn-298, a residue involved in a hydrogen-bond network near Y Z We found that the D1-N298A mutant of Synechocystis sp. PCC 6803 exhibits an O 2 evolution activity of ∼10% of the wild-type. D1-N298A and the wild-type D1 had very similar features of thermoluminescence glow curves and of an FTIR difference spectrum upon Y Z oxidation, suggesting that the hydrogen-bonded structure of Y Z and electron transfer from the Mn 4 CaO 5 cluster to Y Z were little affected by substitution. In the D1-N298A mutant, however, the flash-number dependence of delayed luminescence showed a monotonic increase without oscillation, and FTIR difference spectra of the S-state cycle indicated partial and significant inhibition of the S 2 → S 3 and S 3 → S 0 transitions, respectively. These results suggest that the D1-N298A substitution inhibits the proton transfer processes in the S 2 → S 3 and S 3 → S 0 transitions. This in turn indicates that the hydrogen-bond network near Y Z can be functional as a proton transfer pathway during photosynthetic water oxidation., (© 2017 by The American Society for Biochemistry and Molecular Biology, Inc.)

The chloroplast-type F(1) ATPase is the key enzyme of energy conversion in chloroplasts, and is regulated by the endogenous inhibitor epsilon, tightly bound ADP, the membrane potential and the redox state of the gamma subunit. In order to understand the molecular mechanism of epsilon inhibition, we constructed an expression system for the alpha(3)beta(3)gamma subcomplex in thermophilic cyanobacteria allowing thorough investigation of epsilon inhibition. epsilon Inhibition was found to be ATP-independent, and different to that observed for bacterial F(1)-ATPase. The role of the additional region on the gamma subunit of chloroplast-type F(1)-ATPase in epsilon inhibition was also determined. By single molecule rotation analysis, we succeeded in assigning the pausing angular position of gamma in epsilon inhibition, which was found to be identical to that observed for ATP hydrolysis, product release and ADP inhibition, but distinctly different from the waiting position for ATP binding. These results suggest that the epsilon subunit of chloroplast-type ATP synthase plays an important regulator for the rotary motor enzyme, thus preventing wasteful ATP hydrolysis.

In F1-ATPase, the rotation of the central axis subunit gamma relative to the surrounding alpha3beta3 subunits is coupled to ATP hydrolysis. We previously reported that the introduced regulatory region of the gamma subunit of chloroplast F1-ATPase can modulate rotation of the gamma subunit of the thermophilic bacterial F1-ATPase (Bald, D., Noji, H., Yoshida, M., Hirono-Hara, Y., and Hisabori, T. (2001) J. Biol. Chem. 276, 39505-39507). The attenuated enzyme activity of this chimeric enzyme under oxidizing conditions was characterized by frequent and long pauses of rotation of gamma. In this study, we report an inverse regulation of the gamma subunit rotation in the newly engineered F1-chimeric complex whose three negatively charged residues Glu210-Asp211-Glu212 adjacent to two cysteine residues of the regulatory region derived from chloroplast F1-ATPase gamma were deleted. ATP hydrolysis activity of the mutant complex was stimulated up to 2-fold by the formation of the disulfide bond at the regulatory region by oxidation. We successfully observed inverse redox switching of rotation of gamma using this mutant complex. The complex exhibited long and frequent pauses in its gamma rotation when reduced, but the rotation rates between pauses remained unaltered. Hence, the suppression or activation of the redox-sensitive F1-ATPase can be explained in terms of the change in the rotation behavior at a single molecule level. These results obtained by the single molecule analysis of the redox regulation provide further insights into the regulation mechanism of the rotary enzyme.